A device manufacturing method and lithographic apparatus may be used, for example, in the manufacture of integrated circuits (ICs). In that circumstance, a patterning device, such as a mask, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern may be imaged onto target portions, including dies or die parts, on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate contains a network of target portions that are successively exposed. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the projection beam in a given direction (the “scanning”-direction), while synchronously scanning the substrate parallel or anti-parallel to this direction.
The method may be at least partially carried out in vacuum, more specifically in a vacuum chamber, and/or at atmospheric pressure. The application of vacuum may be desired, for example, to provide a relatively contamination-free environment to carry out the manufacturing method, so that devices having small features may be made with high precision. The use of vacuum may be desired to prevent absorption of the projection beam.
A problem of the known method is that a large amount of residual water may be present in the chamber, which may lead to degradation, for example, oxidation, of parts of the illumination system and/or the patterning device used in the manufacturing method. The amount of water in the chamber may even rise due to water that originates from the substrates to be treated, which substrates are brought into the chamber from an environment and may include adsorbed water. The degradation of the illumination system and/or patterning device may impair a desired imaging performance of the manufacturing method. The degradation may further lead to high maintenance and operating cost, a low machine life time, a low productivity, which may result in high costs of the devices manufactured thereby.